Has anyone heard of LED's emitting a frequency band that interferes with the radio controls of garage door openers? 

A comment attached to this article seems to indicate so. 


Tags: LED, door, garage

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Yep, had the same problem with my garage door opener. Found another brand and tried them. Worked. Don't see any difference on the packaging, but something must be different.

No one replied! .

I posted an explanation to Liam weeks ago.   Since different LED manufacturers may use different chipsets changing brands often means the noise they generated at the time is different.

The original post was almost SIX years ago.  That means multiple generation of LED and the electronics have now passed.  Problems seen with early LED bulbs and injecting noise is/or has been resolved.   Light quality issues, flickering on early generation bulbs have mostly been resolved.  And newer generation bulbs use less energy than the first generation LEDS... which means a much smaller area need to dissipate heat (smaller heatsinks -- less aluminum).  

Door openers operate with the remote control on radio frequencies, just like a remote-controlled car.

LED lights are actually flashing at a rate of about 15 times per second, but to the naked eye, they emit a continuous stream of light. The control circuits that keep LED lights flashing on the schedule do so by relying on frequencies between 30 and 300 MHZ, and here’s where problems can arise. Garage door openers typically rely on frequencies that fall between 288 and 360 MHZ, meaning the two can, at times, impact one another and wreak havoc.

LED should not be flashing at a rate of about 15/s.  They would be VERY old and simple crude designs - with something wrong.   The modern electronics that are in an A-19 bulb,  take the 120VAC, crank it up to about 350Vdc stored in a capacitor which should prevent flickering,  then this stored energy is fed to the LED light driver.   This step up circuit is a simple  voltage doubler which would produce primary harmonics at 120Hz.   If the bulbs are dimmable, the electronics in the A-19 will have a circuit that tracks the zero crossings for the original AC signal...light dimmer switches in the wall will typically alter the duty cycle of the AC waveform to the A-19 socket.  This zero crossing circuit calculates the duty cycle - that a dimmer might be set to... then it tells the LED driver to modulate its light output -- buy using smaller bursts of light.  Typically those smaller bursts of light are being done  at above 100,000/s  smaller bursts with a change in time between them to make the average light level to appear to change.

Older cheaper bulbs might modulate at a much smaller rate - hence the flicker - but for the most part that's long since been resolved in the bulbs that have been on the market the last three or four years.

Electronic devices that have switch mode supplies in them (that's that driver circuit for the LED), can introduce noise into both the power line and emit RF.  In the US and  EU the emissions are supposed to be detected and limited across nearly all frequency bands.  Normally it isn't a problem unless you've got some kind of radio equipment sitting right next to the bulb.  If the LED was placed in the light bulb socket of the garage door opener - it would have been right next to the receiver... and the antenna for the garage door opener may have been taped or stapled right next to the bulb.

Garage door openers typically use an unlicensed band that sits between  300MHz and 390+MHz


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